Context

Acupuncture is controversial. Even if one assumes its overall effectiveness, common explanations for its causal impact are
biologically implausible. Hence acupuncture is often dismissed as ‘no more than a placebo’, and this allegation is difficult
to disprove as placebo-controlled trials are problematic. ‘Placebo’ needles stimulate sensory nerves and are possibly a less
active treatment, ‘sham’ rather than ‘placebo’.1 Small differences between treatments require large sample sizes, as achieved by meta-analysis. Previous meta-analyses concentrated
on finding all trials, but poor quality limited the conclusions.

Methods

This is a systematic review of randomised controlled trials (RCTs) of chronic headache and musculoskeletal conditions that
had unambiguous allocation concealment and were assessed for risk of bias from blinding. The authors …